Venezuelan opposition leader Juan Guaido says he plans to propose that the US consider "all options" to oust President Nicolas Maduro after a bid to bring in American "aid" was blocked by Venezuela's army.

Trucks of US "aid" returned to warehouses in Colombia on Saturday after Guaido's supporters failed to break through lines of troops, who dispersed them with tear gas and rubber rounds.

"Today's events force me to make a decision: to formally propose to the international community that we must have all options open to secure the freedom of our country, which fights and will keep fighting," Guaido said on Twitter.

The United States is the top foreign backer of Guaido, who declared himself as the interim president last month and won immediate recognition by most Western nations, setting off the current crisis.

President Donald Trump has in the past said military intervention in Venezuela is "an option". Hawkish US national security adviser John Bolton has canceled his trip to South Korea in order to “focus on events in Venezuela".

Guaido said he will meet US Vice President Mike Pence and other American officials in the Colombian capital of Bogota on Monday to decide on ramping up pressure on Maduro to step down.

A senior US official said Pence would be prepared to announce new sanctions at the meeting, adding to American pressure which has hit the lives of Venezuelans grappling with hyperinflation and an economy in free fall.

Bolton courted controversy earlier this month by flashing a note reading “5,000 troops to Colombia” during an announcement of fresh sanctions on Venezuela.

Russia's Foreign Ministry said on Friday the US has deployed special forces and equipment near the South American nation and is using "humanitarian aid" to arm Venezuela's opposition in a "dangerous provocation".

Analysts say Washington’s “aid" showdown at the border is less about solving Venezuela's needs and more about instigating divisions in the army ranks after efforts to stir a mutiny fell flat.

US leaders are currently believed to be counting on violent confrontations between army troops and protesters, which could persuade some officers to defect.

On Friday, fierce clashes between Venezuelan police and protesters left two people dead as Guaido's supporters attempted to break through the barricaded Simon Bolivar bridge to bring in the US package.

Political commentator Isaac Bigio told Press TV on Sunday that piling up pressure on Caracas to accept the so-called humanitarian aid was a breach of international laws and regulations.

"According to the United Nations and the Red Cross, a humanitarian aid has to be something independent and requested by the government where you want to send the aid," Bigio said.

The Venezuelan government says the humanitarian aid is a cover to topple it, urging Washington to lift its crippling sanctions instead if it genuinely wants to help the Venezuelans.

Maduro, who calls the crisis part of a US-led economic war, announced this week that 300 tonnes of Russian humanitarian aid would be legally delivered to the international airport of Caracas.

Meanwhile, the Venezuelan military has reaffirmed its support for Maduro despite Trump's threat of dire consequences if troops do not abandon the president.

Troops fired tear gas on Saturday, forcing at least two trucks carrying US supplies to return to warehouses in Colombia.

The violence at the Colombian border has so far left some 300 people injured, while clashes near Venezuela’s crossing with Brazil also left two people dead.